lodash reduce by key code example

Example: lodash map

_.each(markets, (obj, key) => {   obj.symbol = key})console.log(markets)//=> {       'BTC/USD': { buys: 0, sells: 3, symbol: 'BTC/USD' },       'DASH/BTC': { buys: 3, sells: 1, symbol: 'DASH/BTC' },       'ETH/BTC': { buys: 3, sells: 2, symbol: 'ETH/BTC' }    }